Autonomous Factory · wind-up walker

Trotter

A desk-scale quadruped in the Spot silhouette, rebuilt in CAD as a wind-up walker. Twist the knob at the tail, set it down, and it trots off on four legs. No motor, no battery, no electronics — a single rubber band drives two crankshafts.

56 printed parts 1 rubber band 144.8 g in PETG 44.1 mm per crank turn
Intro clip

Wind it up.

56 parts, one band.

Every piece here came off a printer — shafts, gears, rods, pins and caps included. The only bought part is a rubber ring. Keep scrolling to wind it up and walk it.

Wind the knob.

The fluted knob at the tail turns a double-D shaft. 30 to 50 turns twist one 45 mm rubber band, doubled over a 100 mm span down the middle of the chassis.

Lid off.

The band runs from a front anchor pin back to the winder hook. No spring, no motor, no cell — the twist in that band is the entire power supply.

Sixteen teeth into eight.

The winder pinion meshes a crown gear on the rear crankshaft, 16 teeth into 8. Two coupling rods tie the rear cranks to the front pair, so all four discs stay in phase.

Cranks become steps.

Each leg hangs on a crank pin 4 mm off axis and rocks against a fixed guide pin 20 mm above it. That geometry alone makes a step: 8 mm of lift, ±11.3° of swing, knees rigid at 76.5°.

44.1 millimetres a turn.

Diagonal pairs land together — front-left with rear-right — so two feet are always down. One crank revolution carries it 44.1 mm; a full wind walks it 0.66 to 1.1 m across the desk.

56 printed parts, six jobs.

Each part is exported in its assembled pose, so the colours key to the parts themselves rather than being painted on afterwards. Pick a job to see which pieces do it.

Trotter standing on a pale oak desk beside a window in morning light

Built for a desk.

148 × 109 × 121 mm overall — about the footprint of a paperback. It walks on anything flat: a desk, a kitchen table, a hard floor. Wind, set down, let go.

Direct side profile of Trotter showing the bent knees and the flat blade above each hip
Side profile: knees fixed at 76.5°, and the flat blade above each hip that carries the guide slot.
A hand winding the tan fluted knob at the tail of the robot
Winding is the whole interface — three fingers on the tan knob.
Exploded view of the walker with the lid, panels, crankshafts, legs and fasteners separated
Everything separates: lid, deck panels, crankshafts, rods, legs and caps.
Two children watching Trotter walk across a wooden playroom floor
Nothing to charge and no batteries to go flat.

One band is the only thing you don't print.

0
printed parts
0 g
PETG on the plate
0 h
on the printer
Overall
148 × 109 × 121 mm
Chassis
143 × 56 × 46 mm, 2.5 mm walls
Material
PETG, printed without supports
Bed needed
fits 256 × 256 mm
Crank throw
4 mm (8 mm of foot lift)
Gear train
8-tooth pinion into a 16-tooth crown
Travel
44.1 mm per crank turn
Rubber band
one 45 mm ring, doubled
Wind
30–50 turns, then set it down

Running fits are +0.2 mm per side and press fits 0.1 mm, so the discs and rods turn straight off the plate. Fit the band with the lid off, press the retention caps on once each leg is on its crank pin, then snap the lid down.

Trotter on a white studio background, three-quarter view
Free shipping —
Buy on autonomous.ai See the listing